Stainless steel, cup holder compatible, fits right in your pack—Hydro Flask's reusable, refillable 21 oz Standard Mouth insulated water bottle keeps cold drinks cold for 24 hours, hot drinks hot for up to 12 hours, and holds enough hydration for hours of fun. DETAILS TempShield®️ double-wall vacuum insulation keeps drinks cold up to 24 hours, hot up to 12 Flex Cap is leakproof when closed Honeycomb™️ Insulated Cap for maximum temperature retention Made with 18/8 pro-grade stainless steel for durability, pure taste and no flavor transfer Color Last™ powder coat is durable, sweat-free and colorful BPA-Free Dishwasher safe Not for use on a stove, in a microwave or freezer